Search for missing bushwalker Lily Hooper enters seventh day in NSW

The family of missing bushwalker Lily Hooper is dealing with an "unimaginable situation" as the search for the 18-year-old continues.

Ms Hooper left her home south-west of Sydney last Wednesday morning to go hiking in the Nattai National Park in the Southern Highlands.

Her car was later found near the Bonnum Pic Walking Trail, but despite an extensive multi-agency operation beginning on Wednesday night, there has been no trace of the experienced bushwalker.

'Beloved daughter'

The family released a statement through NSW Police today.

"Our family is absolutely devastated that our beloved daughter Lily is missing," the family said.

"We would like to thank all the emergency services and volunteers for their support and continued commitment to the search, not only during the day but throughout the night."

They wrote that they were "desperate" to bring Lily home safe and asked the community to keep the family and Lily in their thoughts.

"We appreciate people who have made offers for the search, but due to the terrain and conditions we ask just professional search teams continue," the family wrote in the statement.

Search continues

The search is now in its seventh day today, but authorities said they had not given up hope of finding the experienced bushwalker.

Specialist police crews were joined by 200 teams from the SES and rescue helicopters at the command site today, where they have been taking turns to work through the trail day and night.

Crews scoured dense bush, deep ravines and clifftops in their search and have battled inclement weather, which is expected to clear on Thursday.

NSW Police said there had been no trace of Ms Hooper or her belongings, and that her family was assisting in the search effort.

The terrain has been described as "incredibly rough", vast and dense, complicating efforts to cover the search area.

Police previously said they were unable to determine Ms Hooper's intended route beyond the Bonnum Pic Walking Trail, and whether she reached a nearby peak.

They previously said they believed Ms Hooper had her mobile phone with her and they were continuing to examine telecommunications information that could help establish where she went after arriving at the national park.